Throttling snap-action valve



UnitedStates Patent 2,702,052 THROTTLING SNAP-ACTION VALVE Richard D.Grayson, La Canada, Calif., assignor to General Controls Co., Glendale,Calif., a corporation of California Application November 23, 1953,Serial No. 393,788

Claims. (Cl..137630.22)

This invention relates to valve structures of the type which employsover-center snap-action means for operating the valve and means movablegradually in response to variation of a controlling condition, such aspressure or temperature, for actuating the snap-action means.

In the operation of conventional snap-action means from one to the otherof its snapped positions there IS considerable preliminary movement ofthe means before dead-center position is reached, which movementnormally serves no useful purpose. It is an ob ect of this invention totake advantage of one phase of this preliminary movement of thesnap-action means and to apply it to the valve so as to effect gradualthrottling of the flow. I

Another object of this invention is to provide a valve structure, of thecharacter described and incorporating the feature described in thepreceding paragraph, which comprises a main valve and a supplementalvalve operated in sequence by the snap-action means and arranged so thatboth of the valves are snapped substantially simultaneously from closedto fully-open position, while, in

subsequent closing operation of the valves, the main valve is closedgradually and the supplementalvalve is maintained fully-open until it issnapped to closed pos1- tion when the snap-action means passesover-center.

A valve structure as described in the preceding paragraph has particularutility for controlling flow of fuel gas to a main burner. Thesupplemental valve then serves, when the-main valve is closed, to supplygas at an adjusted constant rate sufiicient only for low-fire operationof the particular burner, and normally snaps closed only if the weatheris so mild that the heat produced by the low-fire is in excess of thatrequired. The

full flow of gas passing to the burner through both of v appreciation ofits features and advantages, reference is to be had to the followingdetailed description and.

accompanying drawing, and to the appended claims.

In the drawing: Figure. l is a more-or-less diagrammat c showmg, in

section, of a valve structure embodying this invention;

Figures 2 and 3 are views of the upper part of the valve structure ofFig. 1 showing the parts in different positions assumed in operation;and

Figure 4 is a view, similar to that of F1g. 3, showing a modified valvestructure according to the invention.

Referring first more particularly to Fig. 1 of the drawing, the numeral11 indicates a valve casing having an inlet 12 which leads to a shallowcylindrical chamber 13 defined at its top by a screw cap 14. In thebottom of chamber 13 is a cylindrical port 15 which is connected by abranch opening 16 with the outlet 17 of the casing. Raised around theupper end of port 15 is an annular valve seat 18 upon which a generally(llSklike main closure 19 normally rests. In the upper part of closure19'is a recess 20 and fitting tightly m the I top of this recess is acentrally apertured disk 21, re-

an annular seat 23 upon which a disk-like supplemental By providing aseparate valve for low- Patented Feb. 15, 1955 2 closure 24 normallyrests. The main closure 19 is biased to seated position by the force ofa spring 25 compressed between disk 21 and the cap 14, the supplementalclosure 24 likewise being biased to seated position by the force of arelatively weak spring 26 compressed between it and the cap andextending through the central aperture in disk 21.

Slidable in a central opening through the bottom wall of recess 20 is ahollow cylindrical driving member 27 which is guided in the neck of afunnel-like inward extension 28 of the casing, which extension separatesthe upper and lower interior parts of the casing. In thehollowcylindrical part of the casing below extension 28 are conventionalover-center snap-action means for operating member 27. These meanscomprise a dished snap-disk 29 and a pusher member 30 having an annularknife-edged projection 31 engaging the underside of the snap-diskimmediately adjacent its periphery and forcing the top surface of thedisk against an annular knife-edged projection 32 provided around thebase of extension 28, and engaging the disk on a circle concentric withbut smaller than that defined by projection 31. In Fig. '1 the pushermember 30 is shown in upwardlymoved position and disk 29-snapped tocorresponding shape, the normal or unstressed shape of the disk beingthat shown in Fig. 2. A screw 33 threaded in the closed bottom ofdriving member 27 provides an adjustable connection between the memberand disk 29.

'For actuating the snap-action means, means of j the type adapted tomove gradually in response to variation of a controlling condition, suchas temperature or pressure, are provided. The particular means shownherein by way of example comprise an expansible-contractible bellowsmember 34 and a remote thermal bulb 35 which are interconnected by acapillary tube 36 (extending through a slot 37 in the side of thecasing) and charged with the usual expansible fluid. The top end of thebellows member fits in a shallow recess in the underside of a plunger.38 slidable within the cylindrical lower part of the casing and sealedat its, periphery by an O- ring 39. The bellows member is supported atits bottom by a screw 40 threaded in an opening through a screw cap 41covering the bottom of the casing, a knob 42 being provided foradjusting the screw in accordance with the desired setting of thebellows system. On the top of plunger 38 is a conical projection 43engageable with the pusher member 30 of the snap-action means.

The operation of the valve structure shown in Figs. 1-3 will bedescribed in connection with the control of supply of fuel gas to a mainburner indicated in Fig. l

' by numeral 44 and for the igniting of.which a continuously burningpilot burner 45 is provided, it being assumed that the thermal bulb 35is then arranged to respond to the temperature of a space heated by themain burner.

In Fig. 1 the parts are shown in the positions assumed when therequirement for heating is satisfied, so that the bellows 34 is expandedand snap-disk 29 so flexed that the, driving member 27 is in a fallenposition and the tip of this member spaced by a considerable distancefrom the supplemental closure 24. Both the supplemental closure and themain closure 19 are therefore seated under the force of springs 26 and25 so that flow from the inlet chamber 13 is completely obstructed.

In response to fall of space temperature bellows 34' contracts and in sodoing permits flattening of the snapdisk under itsown resilience so thatthe driving member 27 is moved gradually upwards. The arrangement issuch that this member is free from engagement with supplemental closure24 until the snap-disk is forced beyond its dead-center or. flatposition and consequently moves suddenly past-center to assume itsalternate dished shape as shown in Fig. 2.- In the corresponding suddenupward movement of the driving member and the supplemental closure thelatter engages a disk 21 (fixed to the main closure 19) and by continuedmovement forces the main closure away from its seat. The parts are thenin the positions shown in Fig. 2 wherein, as indicated by the arrows inthat figure, gas can flow to the main burner from inlet chamber 13, notonly past the main valve seat 18, but also in a supplemental path:through the opening 22, past the supplemental valve seat 23, throughopenings 46 and 47 in the hollow driving member, openings 48 in disk 29and openings 49 in pusher member 30 to the space below that member, andthence by way of openings 50 and 51 in the casing to outlet 17. The gasnow flowing in large amount to the main burner is readily ignited by thepilot burner, and a high-fire condition is established.

When, because of the high fire, the space temperature then rises,bellows 34 expands causing the center of the snap disk to fall so that,under the force of springs 25 and 26, the driving member and the closureassembly move downwards and the space between the main closure and itsseat 18 is gradually reduced so that fiow to the main burner isthrottled. When, by this movement, the main closure finally engages itsseat, flow through the casing. is restricted to the supplemental pathdescribed in the preceding paragraph, the parts then being in thepositions shown in Fig. 3. The rate of this flow can be adjusted bymanipulation of a flow restrictor 52, provided in opening 50 andaccessible at the enterlor of the casing, to determine the low-firesetting suitable for the particular main burner employed. It Will. beobserved that when the main closure seats, the snap disk is close to,but still above, its dead-center or fiat position.

In operation of the system while the weather IS relatively cold, themain closure normally remains within its throttling range, movinggradually in either direction between fully-open and closed position inaccordance with the heating requirements of the space. The supplementalpath for restricted fiow' of gas sufiicient only for minimum low-fireoperation of the burner permits such full-range operation of the 'mainvalve.

When, however, the weather is mild and even the small amount of heatproduced by the low fire is in excess of requirements, continued rise ofspace temperature effects such movement of the snap disk that it finallyreaches dead-center position and then snaps past-center to the positionshown in Fig. 1 wherein flow to the main burner is completelyobstructed.

In this movement of the snap disk toward dead-center (from the positionof Fig. 3) the supplemental closure 24 moves slightly downwards towardits seat under the force of spring 26. However, the screw 33 at thebottom of the driving member is adjusted so that until the supplementalvalve finally snaps closed its flow capacity is still considerably inexcess of theflow capacity of the restricted opening 50 because of thelarge diameter of the supplemental seat 23.

When, in its throttling movements, the main closure seats, the force ofspring 25 is relieved so that, especially since spring 26 is relativelyweak, there is then considerably less force acting downwardly on thesnapdisk and the bellows. It has been found that because of thisreduction of force the space temperature must then rise proportionatelyhigher before the snap action occurs, so that there is less frequentshut-off of the main burner.

The simplified form of the invention shown in Fig. 4 (and wherein theparts are in the same operative positions as in Fig. 3) differsmaterially from that of Figs. l3 only in that the driving member,instead of being hollow, is a solid rod 60, and a fixed resistor 61,threaded in an opening through the main closure 19', is provided for thesupplemental flow through the casing as indicated by the arrows. Theoperation of the valve structure of Fig. 4 is obviously the same as thatdescribed above in connection with the structure of Figs. l-3. To changethe rate of supplemental flow, the restrictor 61 is removed and anotherrestrictor of suitable flow-capacity substituted.

The specific embodiments of my invention herein shown and described areobviously susceptible of modification without departing from the spiritof the invention, and I intend therefore to be limited only by the scopeof the appended claims.

I claim as my invention:

1. In a valve structure: a main valve and a supplemental valve; aconnection for operating said valves in such sequence that thesupplemental valve opens before the main valve opens and subsequentlycloses after the main valve closes; over-center snap-action means foroperating said connection; means for applying force to said snapactionmeans so as to effect gradual movement of the same toward itsdead-center position in alternate directions; and lost-motion means insaid connection arranged taneously from closed to full-open positiomsaidconnection being such that subsequent closing operation of the valveseffects, before the snap-action means reaches dead-center position,gradual closing of the main valve and maintenance of the supplementalvalve in substantially full-open position until the snap-action meansreaches dead-center.

2. In a valve stru ture; a casing having a main passage and a restrictedpassage for flow through the casing to a common outlet; a main valve anda supplemental valve for controlling flow through said main passage andsaid restricted passage, respectively; means, including overcentersnap-action means, for operating both of said valves; and means movablegradually in response to variation of a controlling condition foractuating said operating means; said operating means being adapted toeffect. when actuated in response to variation of said condition in onesense, snap-action operation of both of the valves directly from closedto fully-open position, and, upon subsequent variation of the conditionin the opposite sense and before said snap-action means reachesdead-center position, gradual closing of said main valve to throttleflow through said main passage, and, with continued variation of thecondition in said opposite sense after the main valve is fully closed,snap-action closing of the supplemental valve when the snap-action meanspasses overcenter; the flow capacity of the supplemental valve prior toits snap-action closing being greater than that of said restrictedpassage.

3. In a valve structure: a casing having a main passage and a restrictedpassage for flow through the casing to a common outlet; a main valve anda supplemental valve 'for controlling flow through said main passage andsaid restricted passage, respectively; over-center snap-action means;means movable gradually in response to variation of a controllingcondition for actuating said snap-action means; and a connection fortransmitting movements of the snap-action means to said valves so thatsnap-action operation of both of the valves directly from closed tofully-open position is effected when the snap-action means snapsover-center with variation of said condition in one sense; saidconnection being arranged to effect such sequential operation of thevalves that upon subsequent variation of the condition in the oppositesense, and before the snap-action means reaches dead-center position,the main valve is operated gradually toward closed position to throttlefiow through said main passage, and only upon continued variation of thecondition in said opposite sense after the main valve is fully closeddoes snap-action closing of the supplemental valve occur when thesnap-action means again passes over-center; the flow capacity of thesupplemental valve prior to its snap-action closing being greater thanthat of said restricted passage.

4. In a valve structure: a casing having a main passage and a restrictedpassage for flow through the easing to a common outlet; a main valve anda supplemental valve for controlling flow through said main passage andsaid restricted passage, respectively; means biasing both of said valvesto closed position; over-center snap-action means; means movablegradually in response to variation of a controlling condition foractuating saidsnap-action means; means for transmitting movement of thesnapaction means to said supplemental valve so that when the snap-actionmeans snaps over-center with variation of said condition in one sensethe supplemental valve is moved suddenly from closed to fully-openposition; and

a lost-motion connection between the supplement valve and the main valvesuch that continued movement of the supplemental valve from saidfully-open position under the force of the snap-action means efiectsopening of the main valve; said movement-transmitting means beingarranged to efiect, upon subsequent variation of said condition in theopposite sense and before the snap-action means reaches dead-centerposition, gradual closing of the main valve under the force of its biaswhile the supplemental valve is still fully open, and, with continuedvariation of the condition in said opposite sense, sudden movement ofthe supplemental valve under the force of its bias from substantiallyfully-open to closed position when the snap-action means again passesover-center.

5. In a valve structure: a valve casing having a. main passage and arestricted passage for flow through the casing to a common outlet; avalve seat in said main passage; a main closure mounted for movementnormal s hat both of said valves are snapped substantially simulto saidseat out of and into engagement with the seat to control flow throughthe main passage, and biasedjo seated position; said main closure havingan opening therethrough forming, at least in part, said restrictedpassage; a supplemental closure controlling fiow through said openingand biased to closed position; over-center snap-action means; meansmovable gradually in response to variation of a controlling conditionfor actuating said snap-action means; means for transmitting movement ofthe snap-action meansto said supplemental closure so that when thesnap-action means snaps over-center with variation of said condition inone sense the supplemental closure is moved suddenly from closed tofully-open position; and a lost-motion connection between thesupplemental closure and the main closure such that continued movementof the supplemental closure under the force of the snap-action meanseffects full-opening of the main closure; said movement-transmittingmeans being arranged to effect, upon subsequent variation of saidcondition in the opposite sense and before the snap-action means reachesdead-center position, gradual seating of the main closure under theforce of itsbias while the supplemental closure is still fully open,and, with continued variation of the condition in said opposite sense,sudden movement of the supplemental closure under the force of its biasfrom substantially fully-open to closed position when the snap-actionmeans again passes over-center.

6. In a valve structure: a casing having a passage therethrough providedwith a valve seat; a main closure mounted for movement normal to saidseat out of and into engagement with the seat to control flow to theoutlet of the casing, and biased to seated position; said main closurehaving an opening through which fluid can pass through the casing tosaid outlet when the main closure is seated; a supplemental closuremounted for movement out of and into seating engagement with the mainclosure to control flow through said opening, and biased to seatedposition; a first lost-motion connection, between said closures,arranged so that continued movement of the supplemental closure after itis moved to open position effects movement of the main closure to openposition; over-center snap-action means; means, including a secondlost-motion connection, for transmitting movement of said snap-actionmeans to the supplementalclosure; and means movable gradually inresponse to variation of a controlling condition for actuating j saidsnap-action means; said second lost-motion connection being arranged sothat upon variation of said condition in one sense both of the closuresare moved suddenly by the snap-action means from seated to fully-openposition; said movementtransmitting means being arranged to efiect, uponsubsequent variation of the condition in the opposite sense and beforethe snap-action means reaches dead-center position, gradual seating ofthe main closure under the force of its bias while the supplementalclosure is still fully open, and, with continued variation of thecondition in said opposite sense, maintenance of the supplementalclosure in substantially fully-open position until the snapaction meansagain passes over-center and thereby effects snap-action closing of thesupplemental closure.

7. In a valve structure: a casing having a passage therethrough providedwith a valve seat; a disk-like main closure movable out of and intoengagement with said seat to control flow to the outlet of the casing; amain spring biasing the main closure to seated position; the mainclosure having an opening therethrough communicating with said outletwhen-the main closure is seated; a disk-like supplemental closure at theside of the main closure away from said seat and movable out of and intoengagement with the main closure to uncover and cover said opening; asupplemental spring biasing the supplemental closure to seated position;an elongated driving member having an end portion projectable throughsaid opening into operative engagement with the supplemental closure; alost-motion connection between the closures arranged so that movement ofthe supplemental closure in a direction away from its seat efiectssubsequent unseating movement of the main closure; over-centersnapaction means for operating said driving member; and

' means movable gradually in response to variation of a controllingcondition for actuating said snap-action means; said driving memberbeing of such length that when operated by the snap-action means in adirection toward the supplemental closure it is out of engagement withthe supplemental closure until the snap-action means passes over-center;the amount of past-center movement of the snap-action means beingsuflicient to thenefiect sudden movement of both closures to fully-openposition, and, upon subsequent movement of the snap-action means in theopposite direction, gradual movement of the main closure to seatedposition and then sudden release of the supplemental closure, while thesame is in substantially fully-open position, when the snap-action meansagain passes over-center.

8. In a valve structure: a casing having a main passage therethroughprovided with a valve seat; a disklike main closure movable out of andinto engagement with said seat to control flow to the outlet of thecasing; a main spring biasing the main closure to seated position; adisk-like supplemental closure at the side of the main closure away fromsaid seat andmovable out of and into seating engagement with the mainclosurecentrally thereof; a supplemental spring biasing the supplementalclosure to seated position; the main closure having a central openingtherethrough; an elongated driving member in said opening and slidablyfitting the same, said member having an end portion operativelyengageable with the supplemental closure; said member being hollow sothat fluid can enter it when the supplemental closure is in openposition; means defining a supplemental passage, separate from said mainpassage, interconnecting the hollow of the member and said outlet: 21lost-motion connection between the closures arranged so that movement ofthe supplemental closure in a direction away from its seat effectssubsequent unseating movement of the main closure; over-centersnap-action means for operating said driving member; and means movablegraduallyiin response to variation of a controlling condition foractuating said snap-action means; the member being of such length thatwhen operated by the snap-action means in a direction toward thesupplemental closure it is out of engagement with the same until thesnap-action means passes over-center; the amount of past-center movementof the snap-action means being suflicient to then effect sudden movementof both closures to fully-open position, and, upon subsequent movementof the snap-action means in the opposite direction, gradual movement ofthe main closure to seated position and then sudden release of thesupplemental closure, while the same is in substantially fully-openposition, when the snap-action means again passes over-center.

9; A valve structure according to claim 8, and including an adjustablefiow-restrictor in said supplemental passage and accessible at theexterior of the casing.

10. In a valve structure: a casing havinga passage therethrough providedwith a valve seat; a disk-like main closure movable out of and intoengagement with said seat to control flow to the outlet of the casing; amain spring biasing the main closure to seated position; the mainclosure having a restricted opening therethrough communicating with saidoutlet when the main closure is seated; a disk-like supplemental closureat the side of the main closure away from said seat and movable out ofand into engagement with the main closure to control flow through saidrestricted opening; a supplemental spring biasing the supplementalclosure to seated position; the main closure having also a centralopening therethrough; an elongated driving member in said centralopening and slidably fitting the same, said member having an end portionoperatively engageable with the supplemental closure; a lost-motionconnection between the closures arranged so that movement of thesupplemental closure in a direction away from its seat effectssubsequent unseating movement of the main closure; over-centersnap-action means for operating said driving member; and means movablegradually in response to variation of a controlling condition foractuating said snap-action means; the member being of such length thatwhen operated in a direction toward the supplemental closure it is outof engagement with the same until the snap-action means passesover-center; the amount of past-center movement of the snap-action meansbeing suflicient to then etfect sudden movement of the closures tofully-open position, and, upon subsequent movement of the snap-actionmeans in the opposite direction, gradual movement of the main closure toseated position and sudden release of the supplemental closure while thesame is in substantially fully-open position.

No references cited.

